Math question - Page 12

Posted by harry k on October 8, 2009, 10:38 am

> SteveB wrote:

> > How do I figure the area of a pool from the perimeter? =A0It is a kidne=

> > shaped (exaggerated) pool.
> > Steve

> 1. Measure the perimeter. Write it down on a scrap of paper. Throw the
> paper away.
> 2. Find your pool on google earth or google maps satellite view.
> 3. Print it, being sure to include something in the print which is easy
> to measure. (deck, section of fencing, etc.)
> 4. Weigh the print.
> 5. Carefully cut out the pool. Weigh the pool
> 6. Using the actual length of the easy to measure object, determine the
> area represented by the entire print.
> 7. Fill in:
> mass of pool cutout =A0 =A0 =A0 =A0 area of pool (unknown)
> ------------------- =A0 =A0=3D =A0 =A0 --------------------
> mass of entire print =A0 =A0 =A0 =A0area of entire print
> 8. Do the math: (mass of pool) * (area of entire print) / (mass of
> entire print) =3D (area of pool)

I like it. Could use a string, stretch it carefully around the pool
edge, measure length, solve for diameter of circle, solve for area.

Harry K

Posted by Doug Miller on October 8, 2009, 1:01 pm

> Could use a string, stretch it carefully around the pool
>edge, measure length, solve for diameter of circle, solve for area.

That would give only an upper limit to the area. The greater the deviation of
the shape from circular, the greater the deviation of the computed area from
the actual area.

Posted by harry k on October 8, 2009, 1:10 pm

On Oct 8, 10:01=A0am, spamb...@milmac.com (Doug Miller) wrote:

> In article <e9d45005-2d7d-4227-9133-04b3c6fc6...@b3g2000pre.googlegroups.=

> > Could use a string, stretch it carefully around the pool
> >edge, measure length, solve for diameter of circle, solve for area.

> That would give only an upper limit to the area. The greater the deviatio=

n of

> the shape from circular, the greater the deviation of the computed area f=

rom

> the actual area.

True, I overlooked that. My solution wouldn't even come close.

Harry K

Posted by David Combs on November 2, 2009, 1:39 am

>I like it. Could use a string, stretch it carefully around the pool
>edge, measure length, solve for diameter of circle, solve for area.
>Harry K

How about one of those pencil-like things with a wheel on the end,
and you wheel it around the perimeter (on the photo), and
read off the perimeter directly. (Plus converting some units.)

David

Posted by bud-- on October 8, 2009, 12:19 pm

Mike Paulsen wrote:

> SteveB wrote:

>> How do I figure the area of a pool from the perimeter? It is a kidney
>> shaped (exaggerated) pool.
>> Steve

>
> 1. Measure the perimeter. Write it down on a scrap of paper. Throw the
> paper away.
>
> 2. Find your pool on google earth or google maps satellite view.
>
> 3. Print it, being sure to include something in the print which is easy
> to measure. (deck, section of fencing, etc.)
>
> 4. Weigh the print.
>
> 5. Carefully cut out the pool. Weigh the pool
>
> 6. Using the actual length of the easy to measure object, determine the
> area represented by the entire print.
>
> 7. Fill in:
>
> mass of pool cutout area of pool (unknown)
> ------------------- = --------------------
> mass of entire print area of entire print
>
>
> 8. Do the math: (mass of pool) * (area of entire print) / (mass of
> entire print) = (area of pool)

It is an exact answer.

My exact answer is pour 55 gallons of motor oil in the pool (perhaps 0W20).

The oil, of course, floats. Measure the thickness of the oil layer.
Since you know the thickness and the volume, determining the area is
trivial.

--
bud--

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